In this work, we present a fast and flexible 3-D macroscale simulation method for modeling the instantaneous pressure drop and collection efficiency of pleated fibrous filters when exposed to poly-dispersed aerosols in both surface and depth filtration regimes. The simulations are conducted using the Fluent CFD code enhanced with a series of in-house subroutines. A cluster-injection method is developed to accelerate the formation and growth of dust-cake both inside and outside the filter media. Once calibrated with experiment or more accurate microscale simulations, the cluster-injection method can be used to simulate the service life of a pleated filter with reasonable accuracy and CPU time. The simulation methodology developed in this work can be used to design and develop pleated filters for different applications. In particular, it allows one to study the effects of pleat shape, pleat count, filter porosity, fiber diameter(s), flow velocity, aerosol concentration, and particle diameter, as well as the aerodynamic parameters of the flow on the evolution of a filter's pressure drop and collection efficiency overtime. For demonstration purposes, performance of an arbitrary filter with 2 and 4 pleats per inch is simulated when challenged with poly-dispersed particles of 1 to 10 mu m in diameter. For the filter simulated here, it was found that exposure to the above poly-dispersed aerosols results in a shorter service life in comparison to when the filter is exposure to mono-dispersed aerosols with a diameter of 1 or 10 pm having the same mass flux. (C) 2014 Elsevier B.V. All rights reserved.